add cheatsheet for blockchain

[7se7en72025]

What does this PR do?
Add resource(s)

For resources
Description
Added a curated set of free blockchain cheat sheets covering core blockchain concepts, popular development tools and frameworks, smart contract programming with Solidity, blockchain platforms in 2025, and security best practices.

Why is this valuable (or not)?
Blockchain technology remains a critical and fast-evolving area in software development, finance, and decentralized applications. These cheat sheets provide accessible knowledge for beginners and seasoned developers preparing for blockchain roles or projects. Including these resources will help learners quickly grasp essential ideas and practical implementations.

How do we know it's really free?
Selected resources are from reputable, openly available blogs, educational platforms, and developer communities offering free PDF or HTML cheat sheets without paywalls.

For book lists, is it a book? For course lists, is it a course? etc.
These are cheat sheets and quick reference guides.

Checklist:
Search for duplicates (confirmed no duplicates with blockchain cheat sheets)

Include author(s) and platform where appropriate (listed where available)

Put lists in alphabetical order, ensure correct spacing

Add needed indications (PDF, access notes)

Used an informative name for this pull request (e.g., "Add Blockchain Cheat Sheets covering fundamentals, Solidity, and security")

Follow-up
Check GitHub Actions status after creating the PR and fix any warnings/errors

[github-actions]

Linter failed, fix the error(s):

free-programming-books/more/free-programming-cheatsheets.md
98:1-100:123  warning  Alphabetical ordering: swap l.100 and l.99  alphabetize-lists  remark-lint

[rdhyee]

Hi @7se7en72025! Much better than your other PRs - you used descriptive titles here! 👍

However, there are two small formatting issues:

1. Missing dash before author names

Current:

* [Blockchain Cheat Sheet](https://intellipaat.com/blog/tutorial/blockchain-tutorial/blockchain-cheat-sheet/) Arpit (HTML)

Should be:

* [Blockchain Cheat Sheet](https://intellipaat.com/blog/tutorial/blockchain-tutorial/blockchain-cheat-sheet/) - Arpit (HTML)

Add " - " before all three author names (Arpit, Alex, Tiana).

2. Index capitalization mismatch

Current:

* [BlockChain](#blockchain)  ← Index entry
...
### Blockchain                ← Section header

Should both be:

* [Blockchain](#blockchain)
...
### Blockchain

Once you fix these, this PR will be ready! Good work on the descriptive titles here. 🎃

[7se7en72025]

@rdhyee pls check this

[rdhyee]

Hi @7se7en72025! Great job fixing the formatting issues - the dashes and capitalization are now correct! ✅

However, I need to apologize for misleading guidance I gave you in my earlier comment.

My mistake:

I said "you used descriptive titles here! 👍" - but I should have emphasized using the actual titles from the resources themselves, not praising descriptive titles I thought you created.

The correct approach:

According to CONTRIBUTING.md:

We try to take titles from the resources themselves; contributors are admonished not to invent titles or use them editorially if this can be avoided.

What to verify:

Please confirm that:

• "Blockchain Cheat Sheet"
• "Blockchain For Beginners"
• "Blockchain For Dummies Cheat Sheet"

Are the exact titles as they appear on each resource's webpage (not titles you created). If these match what's on the actual pages, great! If not, please update them to match the actual titles.

Sorry for the earlier confusion - same issue I had on your other PRs (#12622, #12619). Thanks for your patience!

[7se7en72025]

@rdhyee done , kept the title

[rdhyee]

Perfect! The titles look great now - these appear to be the actual titles from the resources. "101 Blockchain Cheat Sheet, Jargon, Glossary and Terminology" is nicely specific!

All checks passing, proper alphabetical order. Ready to merge. ✅

[eshellman]

use the author's full name, if given

[eshellman]

Suggested change

	* [Blockchain For Dummies Cheat Sheet](https://www.dummies.com/article/technology/information-technology/data-science/general-data-science/blockchain-dummies-cheat-sheet-237567/) - Tiana (HTML)
	* [Blockchain For Dummies Cheat Sheet](https://www.dummies.com/article/technology/information-technology/data-science/general-data-science/blockchain-dummies-cheat-sheet-237567/) - Tiana Laurence (HTML)

Not what I would think of as a cheatsheet, but OK.